Effect of fly ash- and polyacrylamide-consolidated soil layer on A. splendens growth in a desert in North China

Abstract

Vegetation restoration is an important part of effective desertification control. Consolidated soil layer (CSL) formed by mixing coal fly ash (FA), dry anionic polyacrylamide (PAM) granules, and sandy soil can increase the resistance to wind erosion of the soil. This study further investigated the effect of CSL on vegetation recovery on the sandy land in the Ulan Buh Desert, North China. FA and PAM were applied into the 0–0.3 m depth sandy soil layer at varying application rates to form CSLs (viz. T1 (5%FA + 0.05%PAM), T2 (5%FA + 0.1%PAM), T3 (10%FA + 0.05%PAM), T4 (10%FA + 0.1%PAM), T5 (15%FA + 0.05%PAM), and T6 (15%FA + 0.1%PAM)) where Achnatherum splendens (Trin.) Nevski (A. splendens) was planted. The results showed that the moisture content of T3 and T4 was consistently higher than that of untreated sandy soil (CK) along the 0.1–0.2 m depth soil layer, which was attributed to the increased water holding capacity of sandy soil by FA and PAM via alteration of coarse soil texture by fine-sized FA particles and binding of soil particles by PAM as well as the formation of soil surface crust. As a result, the growth traits of A. splendens including average height, tillers number, and leaf-area coverage were promoted in CSLs during the one-year growth period, with the most distinctly improved final growth traits noted in T4 and T6. The eight-month field observation found that the resistance to wind erosion of CSL with A. splendens cover was significantly improved than that of CK, and the wind erosion rate decreased with increasing FA application rate. The improvement in the resistance to wind erosion of CSL was attributed to the pozzolanic action and filling effect of fine FA particles and adhesive action and inter-particle binding of PAM. A. splendens cover was demonstrated to effectively protect the CSL from being eroded by wind in the field.